Microplastics have become a ubiquitous part of our lives, infiltrating the soil, water, and even our bodies. They’re in the air too, and a new study suggests they’re contributing to the heating of the planet.
The findings, published Monday in Nature Climate Change, show that colored micro- and nanoplastics suspended in the atmosphere may contribute to global warming at a level equal to 16% of that caused by black carbon, or soot. The study adds to mounting evidence that plastic pollution doesn’t just degrade terrestrial and marine ecosystems—it can also influence Earth’s climate.
Prior to this research, “we really didn’t know if these things were even warming or cooling,” co-author Drew Shindell, Nicholas Distinguished Professor of Earth Science at Duke University, said during a press briefing. He worked with a team of atmospheric chemists at Fudan University, led by Professor Hongbo Fu, to precisely measure how microplastics interact with light. Their analysis revealed that the net atmospheric effect of almost all microplastics across a range of optical properties is warming.
Microplastics everywhere, even in the air
Plastic pollution on land and in the ocean gradually breaks down into micro- and nanoplastics, and these particles are so light that they can be lofted into the atmosphere by wind.
Atmospheric plastic concentrations are particularly high over ocean gyres, large systems of rotating ocean currents where plastic accumulates and degrades as pieces bump into each other. For example, the North Pacific Garbage Patch—an enormous floating island of trash between Hawaii and California—is created by the North Pacific Gyre.
Much remains unknown about the concentration and distribution of microplastics throughout the global atmosphere, but in recent years, researchers have been investigating their direct radiative forcing: how they change the balance of energy (or heat) flowing in and out of the atmosphere. This is an important metric for measuring how a gas or an aerosol drives climate change, as those with a heat-trapping effect help global temperatures rise.
How microplastics are heating the atmosphere
A 2021 study published in Nature used previous estimates of how colored microplastics absorb and scatter sunlight to calculate their radiative forcing. The results suggested that these particles have a negligible effect on Earth’s climate—especially when compared with the overall impact of other aerosols that interact with sunlight—though the authors noted that their influence will intensify as plastic pollution worsens.
This new study used a more systematic approach to refine the direct radiative forcing of colored microplastics. Fu and his colleagues used high-resolution electron spectroscopy and atmospheric transport simulations to analyze their optical properties, finding their warming potential to be much higher than the 2021 estimate.
On a global scale, this warming effect is still relatively small. But over ocean regions with high concentrations of plastic, such as the North Pacific Garbage Patch, it can exceed that of black carbon by nearly a factor of 5.
Zamin Kanji, an atmospheric scientist and lecturer at ETH Zurich who was not involved in the study, said the findings are not altogether surprising. “If the plastic particles start to be present in significant amounts, they are bound to have effects on direct and indirect radiative forcing,” he told Gizmodo in an email.
However, “the fact that the concentrations of [micro- and nanoplastics] that we detect in airborne samples is increasing—as the techniques and analytical methods to characterize them are advancing—is definitely worrying,” he said.
Kanji noted that key uncertainties remain about where airborne microplastics are found globally, how different particle sizes are distributed in the atmosphere, and how their physical and chemical properties change over time. The study’s authors acknowledge these limitations but emphasize that their findings clearly point to atmospheric microplastics as a warming agent.
“We’re really confident now that we understand their optics and their net effect on radiation, but we’re not as confident—and we need more measurements from all around the world—to really characterize more precisely how much of the stuff is in the atmosphere,” Shindell said.
